1. Field
The disclosure relates generally to optical fibers having low bend losses.
2. Technical Background
There is a need for low bend loss optical fibers, particularly for optical fibers utilized in so-called “access” and fiber to the premises (FTTx) optical networks. Optical fiber can be deployed in such networks in a manner which induces bend losses in optical signals transmitted through the optical fiber. Some applications that can impose physical demands, such as tight bend radii, compression of optical fiber, etc., that induce bend losses include the deployment of optical fiber in optical drop cable assemblies, distribution cables with Factory Installed Termination Systems (FITS) and slack loops, small bend radius multiports located in cabinets that connect feeder and distribution cables, and jumpers in Network Access Points between distribution and drop cables. It has been difficult in some optical fiber designs to simultaneously achieve low bend loss, low cable cutoff wavelength, and a zero dispersion wavelength between 1300 nm and 1324 nm.
More specifically, it is known that standard single mode fibers that are G.652 standards compliant also have microbend loss when deployed in cable. In order to mitigate this loss, polymer coatings with a low primary modulus may be used to reduce the microbend loss to manageable level. These coatings are typically expensive. One alternate method of reducing micro-bending and macro-bending losses in single moded fiber is to use a down-doped trench situated in contact with fiber core, as part of the fiber profile. However, putting a trench in the profile can negatively impact other optical properties like fiber cable cutoff and dispersion.
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.